1. Field of the Invention
The present invention relates to a method for manufacturing a substrate, and more particularly to a method for manufacturing a substrate with surface structure by employing photothermal effect.
2. Related Art
Recently, many technologies were developed to form micro/nano-structure on surface of a substrate, such as nano-imprinting lithography (NIL), semiconductor manufacturing process or micro-electro-mechanical process (MEM) etc. Although these technologies can be used to fabricate micro/nano-structure, the fabricated process is complex and expensive. For example, when semiconductor manufacturing process or MEMS process is used to fabricate micro/nano-structure, the sample was treated by several processes, including spinning coat, exposure/development, etching and imprinting process. Therefore, it is difficulty and there is high cost to fabricate micro/nano-structure employing these technologies. The NIL technology also need many processes to fabricate template with micro/nano-structure on its surface and then imprint on a substrate. This technology also exhibits it is difficulty to manufacture micro/nano structure surface in large area.
During making a printed circuit board (PCB), there is a process for forming gold fingers (also called as an edge connector). The edge connector is used as an interface for connecting the PCB and outside element through inserting to the outside element. The gold fingers are made with gold because gold has superior conductivity and superior oxidation resistance. However, the cost of gold is very expensive, so only the gold finger is only partially formed with gold using platting or chemical bonding, such as bonding pad. During platting, it is necessary to appropriately control parameters, to avoid some questions such as contamination with other metal and bad adhesion etc.
Furthermore, a subtractive process and an additive process are the methods for making a conductive structure. For the subtractive process, the etching formulation and the etching angle errors result in copper residues. Thus, the subtractive process is not suitable for manufacturing fine circuits. The additive process needs a mask to define circuits, and then to manufacture circuits through copper-cladding processes such as plasma sputtering, electroplating, or electroless plating. In general, the flow of the additive process is rather complicated and the cost is relatively high. Therefore, a method for manufacturing conductive wires through inkjet technology is proposed.
Currently, the method for manufacturing conductive wires through the inkjet technology has already been applied in manufacturing flexible circuit boards. Conventionally, the inkjet technology is used to spray conductive ink with a low melting point on an organic substrate, so as to manufacture a flexible circuit board having conductive wires at a high speed and a low cost. However, the conductive ink should be sintered into a film at a high temperature to form conductive wires and meanwhile to enhance the conductivity thereof. During such sintering process, a sintering temperature of 200° C. is required, and the sintering duration should be over about 30 minutes. Accordingly, residual thermal stress is easily generated between the substrate and the formed conductive wires. Besides the heat treatment, another method is to use ultraviolet (UV) laser to sinter, but this method easily damages the substrate.